1. Field of the Invention
The present invention relates to a winding method and a winding apparatus in which a plurality of conductor wires are wound in parallel around a reel to form a coil, which is dropped into a coil receiving jig.
2. Description of the Related Prior Art
Recently, in developing a motor for electric cars or the like, there is a demand for a motor which can provide a large driving force by increasing the sectional area of the electric wire and causing large current to flow through the same, so that a large driving force may be obtained from a low-voltage electric source that can be mounted in a vehicle. However, an increase in diameter of electric wire makes it rather difficult to perform winding operation and the operation of inserting the coil into the stator core. Further, it has a problem in that the space factor (filling factor) of the electric wire in the slot of the stator core would decline.
In view of this, there has been made an attempt to form a coil by winding a plurality of electric wires in parallel (through parallel winding) to thereby increase the electric-wire sectional area without difficulties in the winding operation and the coil inserting operation. In such parallel winding, it is impossible to use as it is a conventional winding apparatus that uses a rotary nozzle called a flyer. That is, if a flyer, which winds electric wires around a reel by rotating a nozzle paying out electric wires around the reel, were used, a plurality of electric wires would be twisted like a rope, making it difficult in a post-process to insert the coil obtained into the slot of a stator core by a coil inserting device.
Thus, for example, JP 3550372 B discloses a winding manufacturing system which forms windings for a predetermined number of poles connected to each other by repeating winding formation through winding of wires around a reel and detachment of a winding from the reel, the winding manufacturing system comprising: a winding forming means for forming a winding by winding wires around the reel that rotates; a winding retaining means for retaining a winding detached from the reel upon completion of the winding at a predetermined retaining position corresponding to the pole of the winding; and a positional relationship maintaining means for restraining deviation in the positional relationship between the winding retained by the winding retaining means and the reel on which a winding for another pole is being formed by moving the winding retaining means in synchronism with the rotation of the reel.
Further, JP 11-98779 A discloses a winding apparatus in which a plurality of wires supplied from a flyer through a tension nozzle and arranged in a strip-like fashion are wound around a reel, in which there is rotatably provided a dummy drum coaxial with the reel and with substantially the same peripheral length as the reel, and wherein there is provided a dummy flyer for winding wires around the dummy drum integrally with the flyer, the wires being wound simultaneously around the reel and the dummy drum while moving the tension nozzle upwards and the dummy drum downwards at the same speed in synchronism with the rotation of the flyer and the dummy flyer to thereby facilitate the insertion of the coil into a coil insertion jig while preventing twisting and to attain an improvement in terms of filling factor.
However, in the technique as disclosed in JP 3550372 B, it is necessary to rotate the reel and the winding retaining means in synchronism with each other in order to maintain the connection between the coil already wound and retained by the winding retaining means (coil receiving jig) and the coil formed by being newly wound around the reel, so that it is rather difficult to expedite the winding cycle.
In the technique as disclosed in JP 11-98779 A, in which a dummy drum is arranged above the reel, it is necessary to perform winding simultaneously on the reel and the dummy drum by two flyers, so that the size of the apparatus has to be substantially large especially in the height direction, making the construction rather complicated so the apparatus cost tends to be rather high.